Re: [edk2-devel][PATCH v1 1/2] Add the volatile keyword to NvmExpressDxe's Passthru CQs and SQs.

["Ni, Ray" <ray.ni@intel.com>]

If it's to copy from hw to sw memory, why do we need volatile?

Thanks,
Ray

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Oliver
> Smith-Denny
> Sent: Thursday, April 20, 2023 7:41 AM
> To: devel@edk2.groups.io
> Cc: Wu, Hao A <hao.a.wu@intel.com>; Ni, Ray <ray.ni@intel.com>; Wang,
> Jian J <jian.j.wang@intel.com>; Gao, Liming <gaoliming@byosoft.com.cn>;
> Michael Kubacki <mikuback@linux.microsoft.com>; Sean Brogan
> <sean.brogan@microsoft.com>
> Subject: [edk2-devel][PATCH v1 1/2] Add the volatile keyword to
> NvmExpressDxe's Passthru CQs and SQs.
> 
> This updates the relevant functions that expect a non-volatile
> 
> structure to be passed to them to take casts of the CQ and SQ,
> 
> now that they are volatile.
> 
> 
> 
> Cc: Hao A Wu <hao.a.wu@intel.com>
> 
> Cc: Ray Ni <ray.ni@intel.com>
> 
> Cc: Jian J Wang <jian.j.wang@intel.com>
> 
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> 
> Cc: Michael Kubacki <mikuback@linux.microsoft.com>
> 
> Cc: Sean Brogan <sean.brogan@microsoft.com>
> 
> Signed-off-by: Oliver Smith-Denny <osde@linux.microsoft.com>
> 
> ---
> 
>  MdeModulePkg/Bus/Pci/NvmExpressDxe/NvmExpressPassthru.c | 10
> +++++-----
> 
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> 
> 
> diff --git a/MdeModulePkg/Bus/Pci/NvmExpressDxe/NvmExpressPassthru.c
> b/MdeModulePkg/Bus/Pci/NvmExpressDxe/NvmExpressPassthru.c
> 
> index f37baa626a16..1a7e39500ac0 100644
> 
> --- a/MdeModulePkg/Bus/Pci/NvmExpressDxe/NvmExpressPassthru.c
> 
> +++ b/MdeModulePkg/Bus/Pci/NvmExpressDxe/NvmExpressPassthru.c
> 
> @@ -459,8 +459,8 @@ NvmExpressPassThru (
> 
>    EFI_STATUS                     Status;
> 
>    EFI_STATUS                     PreviousStatus;
> 
>    EFI_PCI_IO_PROTOCOL            *PciIo;
> 
> -  NVME_SQ                        *Sq;
> 
> -  NVME_CQ                        *Cq;
> 
> +  volatile NVME_SQ               *Sq;
> 
> +  volatile NVME_CQ               *Cq;
> 
>    UINT16                         QueueId;
> 
>    UINT16                         QueueSize;
> 
>    UINT32                         Bytes;
> 
> @@ -581,7 +581,7 @@ NvmExpressPassThru (
> 
>      return EFI_INVALID_PARAMETER;
> 
>    }
> 
> 
> 
> -  ZeroMem (Sq, sizeof (NVME_SQ));
> 
> +  ZeroMem ((VOID *)Sq, sizeof (NVME_SQ));
> 
>    Sq->Opc  = (UINT8)Packet->NvmeCmd->Cdw0.Opcode;
> 
>    Sq->Fuse = (UINT8)Packet->NvmeCmd->Cdw0.FusedOperation;
> 
>    Sq->Cid  = Private->Cid[QueueId]++;
> 
> @@ -815,14 +815,14 @@ NvmExpressPassThru (
> 
>        // Dump every completion entry status for debugging.
> 
>        //
> 
>        DEBUG_CODE_BEGIN ();
> 
> -      NvmeDumpStatus (Cq);
> 
> +      NvmeDumpStatus ((NVME_CQ *)Cq);
> 
>        DEBUG_CODE_END ();
> 
>      }
> 
> 
> 
>      //
> 
>      // Copy the Respose Queue entry for this command to the callers
> response buffer
> 
>      //
> 
> -    CopyMem (Packet->NvmeCompletion, Cq, sizeof
> (EFI_NVM_EXPRESS_COMPLETION));
> 
> +    CopyMem (Packet->NvmeCompletion, (VOID *)Cq, sizeof
> (EFI_NVM_EXPRESS_COMPLETION));
> 
>    } else {
> 
>      //
> 
>      // Timeout occurs for an NVMe command. Reset the controller to abort
> the
> 
> --
> 
> 2.39.2
> 
> 
> 
> 
> 
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